HW6, problem #1:
Solve ideal and real turbofan with given inputs via the below governing equations:
\
Equations implemented in excel for variable PI_C providing following plots:
300
T/mdot0 [m/s]
250
200
150
real
ideal
100
50
0
0
5
10
15
20
25
30
35
PI_C
MANE4080, Propulsion Systems
Homework #6
1. Plot the specific thrust and specific impulse for an ideal and real turbofan with separate
exhaust streams (specs given below) for variation c from 2 to 30 under the flight conditions
M0 = 0.8, T0 = 220 K, P0 =
MANE4080, Propulsion Systems
Homework #5
Use the following properties for air: = 1.4, R = 287 m2/(s2K), and CP = 1005 J/(kgK).
1) Find the optimum bypass ratio for a turbofan engine designed to operate at flight
conditions M0 = 0.85, T0 = 220 K, and P0 =
MANE4080, Propulsion Systems
Homework #4
Use the following properties for air: = 1.4, R = 287 m2/(s 2K), and C P = 1005 J/(kgK).
1) A stationary gas turbine engine (Brayton cycle) operates with air as the working
fluid between the minimum and peak temper
MANE4080, Propulsion Systems
Homework #1
1)
A highbypassratio turbofan engine is tested on a static thrust stand at sealevel
(U0 = 0, P0 = 100 kPa, and T0 = 300 K). The following is measured: the air mass
flow rate through the core is 100 kg/s, the ai
MANE4080, Propulsion Systems
Homework #3
1)
Air flows into the supersonic intake shown below at M0 = 5, T0 = 220 K, and 20
kPa. The air is turned twice through angles of 15 degrees by a center body
causing two oblique shock waves. Following the oblique s
MANE4080, Propulsion Systems
Homework #2
1) At launch the Space Shuttle main engine has 470 kg/s of gas leaving the
combustion chamber at Pt = 20 MPa and Tt = 4000 K (fuels burned in oxygen
create incredible high temperatures  up to twice as large as th
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Propulsion Systems, MAN E4080
Exam 1 (9/23/13)
Problem 1 (74 points)
Consider the RAMJET depicted below. The incoming air (Mo = 4 at static temperature and
pressure of To = 200 K and P0 = 10 kPa, respectively) enters an in
Propulsion Systems, MANE4080
Exam 2; Oct 28, 2013
Name: _
Open book, notes, and calculator. No communication devices.
Problem 1. The turbofan shown below operates at a flight condition of M0 = 1, P0 = 20 kPa, and T0 = 220
K. The turbofan has a bypass rat
Propulsion Systems, MANE4080 Name: S70, M‘l" CM )
Final Exam, Fall 2013
Closed book, notes
3 points per question
1. For subsonic flighr turbojets (circle one) typically provide greater propulsive efficiency,
r]?
2. For a turbofan, increasing the bypass
1
Subsonic Inlets
Weve treated
as a constant for
an inlet but in reality depends on
&
Throat diameter: Maintain a Mach # at throat below M = 1 to be sure flow doesnt go supersonic.
typical
2
Drag

Mounting location also adds significant amount of drag
3
Example
Flight
conditions
Diffuser
Compressor
Burner
Turbine
Nozzle
Properties
M0 = 0.8, T0 = 220 K, P0 = 20 kPa
d = 0.98
See compressor map
See burner maps, b = 0.99
See turbine map below, m = 0.98
n = 0.98, the exit pressure is matched to the
ambient P9
1
Turbomachinery
Turbines & Compressors:
Axial: flow parallel to axis of rotation
Axial compressors and turbines are used in modern/efficient medium to large jet engines.
Centrifugal/radial: flow perpendicular to axis of rotation
Smaller jet engines, tu
1
Nonideal Real cycle analysis continued (AB & TF)
Turbojet with an Afterburner
With an afterburner, we must have 3 sets of properties
Ram:
Diffuser:
(friction),
Compressor:
Burner:
(adiabatic)
,
(thermo losses/aero friction) ,
,
Turbine:
Note:
is the po
1
Turbojet Performance Analysis
In the last two lectures we looked at the specific thrust for nonideal cycles
It is good for design purposes but
For a fixed engine with fixed flow paths only have control over fuel flow (throttle)
Also
varies depending on
1
Lecture 18: Cycle Analysis for a real Turbojet
R doesnt change with temperature: R =
But does change with gas composition
Also use 2
:
use 2 Rs,
(Neglect temperature dependence)
2
Pull out
Unknowns:
where
Also have
(Need to incorporate change in gas
pro
1
Lecture 17: Nonideal Component Performance
Assumptions of ideal Turbojet (and variants)
Other assumptions:
constant at all points in the engine.
Properties: Combustion products are not pure air
2
Ideal compressor:
,
Real compressor:
,
Isentropic effic
1
Lecture 10
Gas Turbines
(Assume
due to ideal cycle assumption)
where
,
Specific thrust (m/s)
approximate
velocity difference
Independent of engine size
Need to understand how engine operation/design controls the ratio
and .
2
Ramjet (Simplest Jet Engine
Lecture 14: Ideal Turbofan
For simple turbojet:
= 0.85 @ 35000ft (
And
Ideally wed like to decrease
=252 m/s)
is poor
to increase
and increase A and
to maintain T.
(will decrease unless f decreased)
Bypass dont use all of the air for combustion.
In this
1
Lecture 15: Propellers
Propellers convert shaft power from an engine into thrust
Propellers are a group of rotating blades or wings oriented such that the direction of the
resultant lift is primarily forward.
Axis of rotation
Flow direction
when
Theorie
1
Lecture 13; Turbojet with Afterburning
PreAfterburner
Diffuser reduces velocity for combustion
Nozzle
Turbine
Fuel
Spray
bar
Flame holder (stabilize flame so it
doesnt blow out back)
Subsonic flow until throat
Recall:
is limited by the turbine material
1
Lecture 16: Turboprops
Propulsive efficiency
Drive
down
Maintain T
o Large Propeller (large )
o Propeller noise and inefficiency at high
o Limited to lower
Propeller efficiency
;
2
Thrust
,
Work Output coefficient: Dimensionless parameter used to descri